Same dates comparing in Java returning -1

try {

		String hql = "SELECT taskDate FROM TaskFutureDates t WHERE t.taskId= : taskId";
		List<java.sql.Date> result = em.createQuery(hql).setParameter("taskId", taskId).getResultList();

		java.sql.Date currentDate =new Date(new java.util.Date().getTime()); 
		
		if (result.size() != 0) {

			for(java.sql.Date date: result)	{
				
				if(date.compareTo(currentDate)>=0) {
				
                   System.err.println("CAST= "+(Date) date);
					return (java.sql.Date) date;
				}
					
			}
		}

	} catch (Exception e) {
		// TODO: handle exception

		//System.err.println(e);
	}
	return null;

}

when I am comparing the two dates I am getting error scenarios

1.when I am comparing alternative days I am getting -1<br/>
eg<br/>
09/04/2020<br/>
10/04/2020

2. when the date is same I am getting -1
   <br/>
   eg <br/>
   10/04/2020<br/>
   10/04/2020

in the 2nd scenario, I should get 0 why the result is -1?

from the compareTo doc:

> a value less than 0 if this Date is before the Date argument

today() (= last midnight) or probably any date from your table is less than now() (which includes the current time)

Although java.sql.Date is supposed to be a date, it actually is still a thin wrapper around epoch milliseconds. It doesn't truncate them. So two java.sql.Date values that are the same date, can still have two different epoch milliseconds values (ie check the getTime() result), and as a result they won't compare identical.

The implementation of the java.sql.Date constructor (Date(long)) is:

public Date(long date) {
    // If the millisecond date value contains time info, mask it out.
    super(date);

}

Contrary to the comment, nothing is masked out. This is probably because java.sql.Date is sensitive to the default JVM time zone, and trying to mask it out would only complicate things.

In any case, since Java 8 / JDBC 4.2, it would be better to use java.time.LocalDate instead of java.sql.Date.

If you can't fully switch to using LocalDate, I would recommend at least using:

LocalDate currentDate = LocalDate.now();
//...
if (date.toLocalDate().compareTo(currentDate) >= 0) {
    // ...
}

Or - as shown in the answer by Basil Bourque - use the specialized comparison methods like isAfter, isBefore and isEqual.

tl;dr

Use modern java.time classes to retrieve and compare stored date values against today’s date.

myResultSet.getObject( … , LocalDate.class ).isAfter( LocalDate.now( "Africa/Tunis" ) ) 

Details

As the correct Answer by Rotteveel explained, you should not be using the terrible class java.sql.Date. That class was years ago supplanted by the modern java.time classes. Specifically, java.time.LocalDate.

As of JDBC 4.2, we can exchange java.time objects with the database. For columns of a type akin to the standard-SQL type DATE, use setObject, updateObject, and getObject to exchange LocalDate objects.

LocalDate ld = myResultSet.getObject( … , LocalDate.class ) ;

To get today’s date requires a time zone. For any given moment, the date varies around the globe by time zone. So while it may be “tomorrow” in Tokyo Japan, it may simultaneously be “yesterday” in Toledo Ohio US.

If you do not specify a time zone, the JVM’s current default time zone is applied implicitly.

ZoneId z = ZoneId.of( "Asia/Tokyo" ) ;
LocalDate today = LocalDate.now( z ) ;

Compare using isEqual, isBefore, and isAfter methods.

Boolean isFuture = ld.isAfter( today ) ;